/**
 *  author:                Timothy Groves - http://www.brandspankingnew.net
 *        version:        1.3 - 2006-11-02
 *                                1.2 - 2006-11-01
 *                                1.1 - 2006-09-29
 *                                1.0 - 2006-09-25
 *
 *        requires:        nothing
 *
 */

var useBSNns;

if (useBSNns)
{
        if (typeof(bsn) == "undefined")
                bsn = {}
        var _bsn = bsn;
}
else
{
        var _bsn = this;
}





_bsn.Crossfader = function (divs, fadetime, delay )
{
        this.nAct = -1;
        this.aDivs = divs;

        for (var i=0;i<divs.length;i++)
        {
                document.getElementById(divs[i]).style.opacity = 0;
                document.getElementById(divs[i]).style.position = "absolute";
                document.getElementById(divs[i]).style.filter = "alpha(opacity=0)";
                document.getElementById(divs[i]).style.visibility = "hidden";
        }

        this.nDur = fadetime;
        this.nDelay = delay;

        this._newfade();
}


_bsn.Crossfader.prototype._newfade = function()
{
        if (this.nID1)
                clearInterval(this.nID1);

        this.nOldAct = this.nAct;
        this.nAct++;
        if (!this.aDivs[this.nAct])        this.nAct = 0;

        if (this.nAct == this.nOldAct)
                return false;

        document.getElementById( this.aDivs[this.nAct] ).style.visibility = "visible";

        this.nInt = 50;
        this.nTime = 0;

        var p=this;
        this.nID2 = setInterval(function() { p._fade() }, this.nInt);
}


_bsn.Crossfader.prototype._fade = function()
{
        this.nTime += this.nInt;

        var ieop = Math.round( this._easeInOut(this.nTime, 0, 1, this.nDur) * 100 );
        var op = ieop / 100;
        document.getElementById( this.aDivs[this.nAct] ).style.opacity = op;
        document.getElementById( this.aDivs[this.nAct] ).style.filter = "alpha(opacity="+ieop+")";

        if (this.nOldAct > -1)
        {
                document.getElementById( this.aDivs[this.nOldAct] ).style.opacity = 1 - op;
                document.getElementById( this.aDivs[this.nOldAct] ).style.filter = "alpha(opacity="+(100 - ieop)+")";
        }

        if (this.nTime == this.nDur)
        {
                clearInterval( this.nID2 );

                if (this.nOldAct > -1)
                        document.getElementById( this.aDivs[this.nOldAct] ).style.visibility = "hidden";

                var p=this;
                this.nID1 = setInterval(function() { p._newfade() }, this.nDelay);
        }
}



_bsn.Crossfader.prototype._easeInOut = function(t,b,c,d)
{
        return c/2 * (1 - Math.cos(Math.PI*t/d)) + b;
}